Unfortunately, there are fishermen that are no longer able to make a living because they have depleted the fish in the area they fish, so now they are looking for a new way to make a living. Farming seaweed seems to be a possible alternative to fishing. We'll be seeing a lot more stories about how great seaweed is as the industry starts to make a market for it.
Feeding cattle grass will reduce the methane just as much as seaweed, I bet. The problem is that the majority of cows are fed a diet of corn, which is cheap relative to grass, which does not appeal to their digestive system so therefore we get a lot of methane out of the whole process. What I see here is somebody trying to sell seaweed as an additive. But the reality is that if you fed cows the proper feed, grass, then we wouldn't have the big problem with methane.
Edit-
Update, seems like grass is a bigger methane producer when digested by cows. The problem is the pollution created to produce and transport the corn. I was going by old info.
Here's a link.
http://newzealmeats.com/blog/grain-fed-vs-grass-fed-beef-gre...